DE3241108A1 - Device for the metered dispensing of partial quantities of viscous substances, such as casting resin - Google Patents

Abstract

A device for the metered dispensing of partial quantities of viscous substances, such as casting resin, from a vertically arranged supply container, especially under reduced pressure, which supply vessel preferably merges at its lower end into a filling housing with an outlet valve, which accommodates a delivery element, especially in the form of a pumping piston. The delivery element dispenses a metered partial quantity as a metered volumetric quantity. In order to reduce inaccuracies regarding this volume, which are caused by the reduced pressure, according to the invention a device is provided above the delivery element, which provides a backpressure in the substance present there, by means of which device the effect of the reduced pressure and the inaccuracy which accompanies this are at least partly compensated.

Description

Device for the dosed delivery of partial quantities of viscous substances, such as casting resin The invention relates to a device for the metered delivery of Subsets of viscous substances, such as casting resin, from a particularly under negative pressure standing, vertically arranged storage container, which at its lower end in a filling housing accommodating a conveying element, in particular in the form of a pump piston passes over with the outlet valve, the conveying element the metered portion as metered Volume dispenses.

Such a device is from DE patent specification 17 78 396 known. A similar device for the metered dispensing, especially of small ones DE utility model specification 72 25 549 shows partial quantities.

Although both devices compared to other known arrangements already have considerable advantages, it can be with certain viscous substances, namely, problems arise in particular for those who tend to absorb gas. this applies in particular to vacuum operation in which the reservoir containing the casting resin Has negative pressure, in particular is kept under vacuum. Such a vacuum operation is z. B. necessary for highly hygroscopic substances, e.g. B. applies this for polyurethane resins. Under these circumstances the dosage may become inaccurate, the exact causes of this inaccuracy could not yet be determined. It is conceivable that the solids content of a certain volume due to gas inclusions is falsified, similar possibilities of error are due to the release of steam conceivable from the viscous substance due to the negative pressure.

These inaccuracies are not very large, but they can be high Quality requirements are quite annoying.

The object of the invention is to improve the known device to the effect that, especially in negative pressure operation, the accuracy of the delivered Subsets will be increased even further.

This object is achieved in that a above the conveyor organ device generating dynamic pressure in the material above the conveying element is provided.

This dynamic pressure generating device ensures that the viscous material pending delivery of a partial quantity not only under the pressure the column of liquid standing above this subset, but in addition also under the back pressure generated by the device, whereby in particular at Vacuum operation occurring inaccuracies can be largely eliminated.

If the viscous substances contain fillers that tend to sediment, it is necessary to stir the substance in the storage container; in order to a uniform mixing of carrier and filler is maintained. In order to No undesired gas inclusions in the viscous during the stirring process If the substance is introduced, vacuum operation is definitely necessary here. Devices of the type mentioned, which have an agitator in the storage container so particularly suitable to them with the measure according to the invention to improve. If such a stirrer is provided in the storage container, it can according to a further development of the invention, this agitator also generates the dynamic pressure, provided it is trained accordingly.

The device generating the dynamic pressure can even be used for this purpose be able to largely eliminate gases already contained in the viscous substance, by being designed in the form of a degassing device known per se.

The device generating the dynamic pressure can - this is a special one favorable construction - be a screw conveyor driven by the agitator. Alternatively but the device generating the dynamic pressure can also be outside the storage container be arranged feed pump, which in turn then takes the form of a screw conveyor could lift.

The screw conveyor or feed pump could also be used in addition to back pressure downwards (i.e. pressure increase to increase the dispensing accuracy) also a dynamic pressure upwards to an outflow opening provided above the material level in the storage container exercise which opening opens onto degassing drainage surfaces. That way I let On the one hand, degassing can be achieved in a particularly simple and compact manner, on the other hand, the increase in back pressure in the area of the metering device, both of which contribute to increasing the dispensing accuracy.

The generation of back pressure can be both downwards and upwards either by the screw conveyor or

Delivery pump two simultaneously working delivery circuits for dynamic pressure has down and up, or else the screw conveyor or feed pump has a reversible conveying direction.

The screw conveyor or feed pump could in the latter case in the agitator and degassing operation an upward dynamic pressure and in the dispensing operation generate a back pressure directed downwards.

Provided that the filling housing is cylindrical and in its upper part Part of the fixed outer housing for the screw conveyor pump that generates back pressure downwards forms, the result is a particularly cheap and compact construction. Something like that applies to yet another embodiment in which the worm of the feed pump worm has a hollow shaft through which the actuating rod for the conveyor element (e.g. B.

Pump piston rod) is passed through.

This hollow shaft, which carries the screw conveyor, can have its own Have a drive and in this case also drive the agitator. The hollow shaft can even carry the agitator itself.

Alternatively, of course, the agitator can also have a drive and in turn drive the hollow shaft via a corresponding gear device or simply because the hollow shaft and agitator again form a component or are at least rigidly connected to each other.

The hollow shaft could in particular be part of an inside the storage container be arranged, back pressure generating upward screw conveyor pump and a Have a screw with a conveying direction that corresponds to the conveying direction of the screw the back pressure is opposite to the downward generating screw conveyor.

The invention is explained in more detail below on the basis of exemplary embodiments explained, which are shown in the drawings.

It shows: FIG. 1 a vertical center section through an inventive Device that generates dynamic pressure Screw conveyor as well comprises an agitator; 2a shows a similar illustration of a further development of the embodiment according to FIG. 1, in which an additional screw conveyor circuit with degassing device is provided; 2b shows a similar embodiment in a similar representation as shown in Fig. 2a, but with one especially for small subsets suitable metering device; and FIGS. 3a, b in a representation similar to that 1 and 2, an embodiment in which the dynamic pressure generating device is arranged outside the storage container.

In Fig. 1, a cylindrical storage container 10 can be seen, the tapers at its lower end and initially into a screw conveyor housing 13 and then merges into a filling housing 14, at the bottom of which one with the room of the screw conveyor housing 13 via a bore 15 communicating outlet valve 16 is located. At its upper end, the storage container 10 is covered by a cover plate 12 limited.

In the filling housing is one of a sleeve body 18, one Carrier plate 22 and a sealing plate 26 formed conveying mechanism arranged, which can be actuated via a centrally guided piston rod 21. The cuff body 18 is in close contact with its outer surface on the inner wall of the filling housing 14 guided to and fro in the housing 14.

The cuff body 18 is provided with a through opening 20, whose clear width is sufficient to allow easy passage of the viscous mass guarantee. The passage opening 20 is from the piston rod 21 interspersed with limited mobility in relation to the cuff body 18 is. At its lower end, the piston rod 21 merges into the driver plate 22, which when the piston rod 21 is raised to the lower one, the storage container 10 facing away side of the cuff body 18 applies and this then from a lower Location back up. When the piston rod 21 moves downward, the exercises In contrast, the driver plate 22 has no effect whatsoever on the sleeve body 18. the Driving plate 22 is in turn provided with passage openings 24, the cross section of which sufficient to ensure the easiest possible passage through the viscous mass.

On the side of the sleeve body facing the storage container 10 18, the piston rod 21 is rigidly connected to a sealing plate 26, the outer diameter of which is larger than the inner diameter of the through opening 20 and which is substantially parallel to the cuff body 18 radially to the piston rod 21 at a distance extends from the driver plate 22, which is greater than the thickness of the between the Driver plate 22 and the sealing plate 26 lying area of the sleeve body 18 is. This sealing plate can move with the downward movement of the piston rod 21 put their underside on the top of the cuff body 18 and closes then the through opening 20 to the storage container 10 or the screw conveyor housing 13 close off.

At the level of the transition between the storage container 10 and the filling housing 14 or screw conveyor housing 13, there may be an annular partition 29, to which the sealing plate 26 in the upper end position of the piston rod 21 lie tightly and thus those located in the storage container 10 or in the screw conveyor housing 13 Can prevent mass from a further inflow into the filling housing 14. This allows For example, with a corresponding construction, removal of the filling housing 14 from the reservoir 10, so that the conveyor mechanism for repair and cleaning work or is also accessible for the purpose of the sleeve body 18, the driver plate 22 or the one located in the screw conveyor housing 13 Replace the screw conveyor 17 with similar elements of different dimensions, which, for example, can be advantageous with regard to the screw conveyor if the viscosity of the mass to be processed is greatly changed.

However, the construction can also be such that the screw 17 is removable upwards, the same applies to the sleeve body 18 or the driver plate 22, if the annular partition 29 is not provided will.

In the storage container 10 there is a one around the piston rod 21 rotatable mixer 32 for mixing the mass in the container 27. The drive device for the mixer - not shown - can be different be trained. For example, the mixer could move up through the cover plate 12 have led out, the piston rod 21 enclosing hollow shaft on the a drive element can be connected. The already mentioned screw conveyor 17 can be mounted and driven in a similar way and even have their own drive have, but it can also, as shown in Fig. 1, at the lower end of the mixer 32 must be attached so that the screw conveyor 17 is rotated with the mixer 32.

A drive for the independent of the drive of the mixer 32 Conveyor screw 17 is particularly advantageous when under certain conditions the mixing process should be interrupted during the filling process or else, if the speed required to operate the screw conveyor 17 is different from that for the Rotation of the mixer 32 required speed deviates more strongly. In the latter However, the drive of the screw 17 by the mixing mechanism 32 could override the case a corresponding, the speed changing gear take place.

Via one which can be seen in FIG. 1 and is fastened, for example, to the cover plate 12 Scale 30, which cooperates with a pointer 31 attached to the piston rod 21, the respective setting of the conveyor mechanism can be observed from the outside.

The operation of the device shown in Fig. 1 is such, that first the piston rod 21 from its sealing position with respect to the possibly existing partition 29 is moved down until the pointer 31 a certain Mark b has reached the position in which the storage container 10 is located Mass 27 on the one hand due to its gravity, but also on the other hand due to the Conveying effect of the conveyor screw 17 rotating in the conveyor screw housing 13 past the sealing plate 26 through the passage opening 20 and the passage openings 24 penetrate through into the interior of the filling housing 14.

When lowering the piston rod 21 to the point with the marking The position marked c places the sealing plate 26 on the upper side of the cuff body 18 sealingly so that the through opening 20 to the storage container 10 or

the screw conveyor space 13 is completed. This will not only the flow of further mass to the filling housing 14 is blocked, but it is at the same time also the effect of a negative pressure prevailing in the storage container 10, how he z. B. for the processing of cast resin because of the required high degree of degassing is necessary, on the interior of the housing 14 canceled. The one on the cuff body 18 adjacent sealing plate 26 then acts together with the sleeve body 18 as Pistons for those that entered the housing 14 during the previous phase Subset of the mass 27. The starting position in which the plate 26 to the sleeve body 18 engages is precisely defined, so that when the piston rod 21 in the lower end position indicated by the marking d is a precisely defined, dem Stroke between the mark c and d proportional portion of the mass 27 through the Bore 15 and the outlet valve 16 delivered will.

Following this, the piston rod 21 is raised again until it in the mark b (or in the absence of the partition 29 also in the mark a) the corresponding situation has returned. During this upward movement, the cuff body becomes 1 8 taken up again and its upper end position corresponds exactly the upper end position of the piston rod 21.

In this way, an exact dosage determined by the stroke volume is achieved allows for a certain subset of viscous mass, as a result of the the screw conveyor 17 generated back pressure inaccuracies in terms of through mass determined by this volume (e.g. as a result of negative pressure Cavities) are largely avoided.

The generation of a negative pressure or a vacuum inside the Reservoir 10 can be made via a valve 37. The whole structure from storage container 10, screw conveyor housing 13 and filling housing 14 can in one be surrounded by a certain distance from a common jacket 33, which together with the container 10 and the housings 13 and 14 delimited a cavity 34 by, for example at the level of the filling housing 14 heating coils 36 can be accommodated, which a heat a thermally conductive medium such as oil or glycerine filled in the cavity 34, so as to bring the viscosity of the mass 27 to a defined value, and so on to facilitate its processing and make it reproducible, if necessary.

The heating effect of the heating coils 36 can be determined by the temperature be controlled in the upper region of the cavity 34 sensing thermostat 38.

In Fig. 2a a construction similar to that in Fig. 1 can be seen, however, degassing devices can also be seen. These exist from drainage plates 23, 25, which are attached to fixed housing parts (such as the drainage plate 23) or on the mixer 32 (drainage plate 25) can. In particular, the drainage plate 25 can also be attached to the housing wall 10. Acts by a conveyor reaching into the mass supply 27 according to FIG it is, in turn, a screw conveyor arranged in a screw conveyor housing 19 20, the mass to be degassed 27 is conveyed upwards, and to one above the Liquid level 28 of the mass to be degassed 27 located outflow opening 34 transported, which opening 34 opens onto the degassing drainage surfaces 23, 25. Gas bubbles contained in the mass are due to the fact that the mass on the drainage surfaces 23, 25 spreads to a very thin layer on the surface of the liquid and thus made to burst, so that the dripping or flowing material is largely guest.

Fig. 3 is a similar representation to FIG. 2, but with the conveyor device 13, 17 or the conveying device directed towards the degassing drainage surfaces 23, 25 to produce 19, 20 is not provided inside the container 10, but is arranged outside became. A screw conveyor was shown as the conveyor device, however, of course, other conveyors can be used just as well. It is essential that in the embodiment shown here at the lower end of the Reservoir 10, a pipe connection 40 is guided to the outside, through which pipe connection 40 located in the storage container 10 mass 27 are withdrawn and in a first Circuit via a first screw conveyor 117 this mass into one above the metering device located space 35 by means of an inflow 41 promotes, which space is preferably is separated from the space of the storage container 10 by a partition plate 36, so as to to increase the back pressure.

Degassing devices are also provided, for example in the form of the degassing drainage plates 25 shown in FIG. 3 is a second one Circuit via a second screw conveyor 120 expediently from the pipe connection 40 withdrawn mass upwards to an opening above the drainage plate 26 second Inflow 42 leads in order to convey mass onto the degassing drain plate 25. The drive the first and second screw conveyor 117, 120 can have a common drive shaft 43 take place, for example by means of a transmission driven by a motor 44. According to Fig. 3a, the pitch of the first and second screw conveyor 117 and 120 opposite, so that when the common shaft rotates at the same time from the Line 40 conveyed mass both in the inflow line 41 and in the inflow line 42 is promoted downwards or upwards. Instead, however, according to FIG. 3b the pitch of the screw of the first and second screw conveyor must be the same. In In this case, however, the direction of rotation must be changed, for example when rotating in the direction of arrow 46, the mass from the line 40 into the line 42 is promoted (mixed and degassing operation), while in the direction of rotation in direction of the arrow 47 material from the line 40 enters the line 41 (metering operation).

In Fig. 2b is a further embodiment similar to that of Fig. 2a shown, but in which the metering device shows a different structure, namely a structure as known from DE utility model 72 25 549 is. This construction is particularly suitable for dispensing small quantities.

As can be seen, the storage container opens - via the screw conveyor 13, 17 - in an approximately cup-shaped chamber 114 which in turn at its lower, the The end remote from the container is closed by an outlet valve 16. The piston In this case, 21 carries a pump piston 39 for displacing mass 27 from the Chamber 114 through outlet valve 16 by means of one on the reservoir 10 facing end of the chamber 114 tightly connected to the inner wall of the chamber Seal 50 with an opening 51, the pump piston 39 being an elongated prismatic or in particular a cylindrical body with the cross section of the opening 51 adapted Cross-section is formed through the seal 50 through tightly into the chamber 114 retractable or completely retractable from the opening 51 by releasing the opening 51 is. It is the seal 50 is preferably made of a resilient material manufactured and takes the piston 39 with its opening 51 under bias. To the The upper and lower boundary surfaces can increase the accuracy of the displaced volume the seal 50 each by a cover plate 52, 53 made of rigid, rigid Material to be completed.

To guide the piston rod 21 and thus the piston 39, it can be useful be to provide a guide disk 54 for the piston rod 21, the openings 55 possesses to let through the mass to be conveyed.

Claims (14)

.P ~ a t e n t a n s p r ü c h ~ e: 1. Device for metered dispensing of subsets of viscous substances, such as casting resin, from a particularly under negative pressure standing, vertically arranged Vorratsein container at its lower end in a / conveying element, in particular in the form of a pump piston, receiving filling housing passes over with the outlet valve, the conveying element the metered portion as metered Dispenses volume amount, characterized in that above the conveyor member (18, 20, 22, 24, 26, Fig. 1; 39, 50, 51, Fig. 2b) one in the above the conveyor organ pending material (27) back pressure generating device (13, 17, Fig. 1; 40, 117, 41, Fig. 3) is provided. 2. Apparatus according to claim 1, wherein the storage container is an agitator having, characterized in that the agitator (32, 13, 17, Fig. 1) the dynamic pressure generated. 3. Apparatus according to claim 1 or 2, characterized in that the dynamic pressure generating device (13, 17, 19, 20, Fig. 2a) at the same time part is a degassing device. 4. Apparatus according to claim 2 or 3, characterized in that the dynamic pressure generating device is a screw conveyor driven by the agitator (32) (13, 17; 19, 20) is. 5. Device according to one of claims 1 to 3, characterized in that that the device generating the dynamic pressure is one outside of the storage container (10) arranged feed pump (Fig. 3a, 3b) is. 6. Apparatus according to claim 4 or 5, characterized in that the screw conveyor or feed pump in addition to back pressure downwards (13, 17; 40, 41, 117) in the direction of the material to be conveyed (27) also creates a dynamic pressure upwards (19, 20; 40, 120, 42) to a mirror above the fabric (28) arranged in the storage container (10) Influence opening (34; 42) exerts which opening (34; 42) on degassing drainage surfaces (23, 25) opens. 7. Apparatus according to claim 6, characterized in that the screw conveyor or delivery pump two simultaneously working delivery circuits (13, 17; 19, 20; 40, 41; 40, 42) for dynamic pressure downwards and upwards. 8. Apparatus according to claim 6, characterized in that the screw conveyor or conveying pump have switchable conveying direction (Fig. 3b). 9. Apparatus according to claim 7, characterized in that the screw conveyor or feed pump in stirring or degassing operation creates an upward dynamic pressure (46 in Fig. 3b) and in the delivery mode a downward dynamic pressure (47 in Fig. 3b). 10. Device according to one of claims 1 to 4, characterized in that that the filling housing (14) is cylindrical and in its upper part (13) the fixed Outer housing (13) for generating back pressure downwards Screw conveyor pump (17) forms. 11. The device according to claim 9, characterized in that the screw (17; 20) of the feed pump worm has a hollow shaft (48; 49) through which the Actuating rod (21) for the pumping element (e.g. pump piston rod) carried out is. 12. The device according to claim 10, characterized in that the Hollow shaft (48; 49) has its own drive. 13. The apparatus according to claim 10, characterized in that the Hollow shaft (48; 49) also carries and / or drives the agitator (32). 14. The device according to claim 10, characterized in that the Hollow shaft (48; 49) part of a back pressure arranged within the storage container (10) upward generating screw conveyor pump (19, 20) and a screw (20) with a conveying direction is that generating the back pressure downwards to the conveying direction Conveyor screw (17) is opposite. Description: